drcook

As the ones of you that subscribe to FIC's emails, they are running a sale right now. So the ones of you more knowledgeable than I in this area, 26 or 30 lb Bosch III's ?

To recap where I am going:

96 LT1 will have the following (which I have on hand, or will)

LT4 Hot Cam
1.6:1 roller rockers
ported heads and intake
headers
might get turned into a 377 (so low miles, doesn't need a rebore, maybe just a quick hone)
4l60E staying with a 3.07 rear gear ratio for cruising, highway, mountain driving

what will the 26's support, I know the 30's will more than do what I need, the 26's are just a tad less in cost


https://fuelinjectorconnection.com/c...l-injector-set

or

https://fuelinjectorconnection.com/c...l-injector-set

aklim

With what will you control the pulse width on the injectors? The stock ECM might not be able to compensate. I tried 30pph on a 383 and it ran pig rich. It had to be tuned.

drcook

I can adjust the pulse width and flow rate inside the tables that the Jet Tuner accesses.

I acquired a base table from an LT4 so I can look at differences and how GM dealt with it also.

Thanks for answering and hope you and yours had a good holiday.

Kevova

IMO you likely need 28lb. I would suggest 26lbs and an adjustable fuel pressure regulator, to tweak fuel pressure up to get fuel trims inline. Be sure injectors are rated at 43.5 psi. Provided pump will deliver 60+ psi. You need too a have a good idea of the crank hp to calculate injector size.

383vett

How could you think you could change displacement and injector flow without a tune?

aklim

I think I read somewhere that a larger injector might have a little more difficulty at idle when adjusting since each millisecond dumps more fuel when it is larger than smaller.

aklim

I didn't think it could adjust that much but if you want to bring it somewhere for tuning, it helps if the car runs enough to get out of the install site and onto a car trailer

Kevova

You will need a somewhat loose converter for idle. PCM can deal with hot cam. Adding 28 ci and depending on airflow from porting. I would expect some tweaking. The OBD2 PCM can compensate for minor changes. Knock system will need some tweaking since lt4 had a unique knock sensor and plug in module

drcook

Back when I was starting the parts acquisition, I spent days searching Craigslist until I found a NOS LT4 Knock module.

STL94LT1

Get the 30's, this will allow for future upgrades. I'm running 33's in my 94 heads/cam LT1 without issue.

drcook

FIC recommended the 30's. I was just asking about the others. Calculations say 32's. They have them in rebuilt also.

The different fuel injector size calculators I have found online say to use 32's (for my targetted HP level) at 80% duty rate.

While I can afford new, I can only afford to buy 1 time, so I have to get it right. I have been doing very careful shopping and have been managing to get most stuff at 60 to 80 % going rate (even new components) by waiting on sales.

Any mileage issues ?

STL94LT1

With a good tune there shouldn't be gas mileage issues, mine still gets 26-28 mpg's on the highway and this is with 6M and 4.10 gears. There should be a table in your tuning software to correct the mpg display with the new injectors.

STL94LT1

I'm running rebuilt Bosch III 32's, the flow sheets actually showed 33#'s.

drcook

Not really related, but just sharing, the new Equinox we got my wife (a 4 cyl turbo diesel) has plenty of power and the best MPG (calculated by the computer) I have gotten so far......50.3 mpg's. It averages 35 to 37 combined.

The sale goes through Monday night. I am going to call them Monday morning and do some more discussing.

FIC told me that if I bought them now, when I was ready to install them, I could send them back and they would check them out and they have a 3 year warranty.

Besides which size, the other dilemma is new or refurbed. From what I have read, injectors really aren't rebuilt as they can't completely take them apart.

aklim

If those recommendations and the calculations agreed I'd go with the 30 then. I'm running 42 on the 383 but that was the tuner who recommended it

aklim

If the pintle is shot, flow will be wrong. If the basket filter is dirty ,flow will be off and they replace it to begin with I'd go reman.

65Z01

The ECM should handle idle and light throttle operation as it uses the O2 sensor(s) to tweak the fuel tables, it's WOT op that requires the tune.
You can scan the tune tables with a monitor tool. I used dyno pulls to tweak FP for best WOT op.

BlowerWorks

Your '96 is sequential - you can run 60's without blinking an eye since you have software to reset injector size.
But ONLY new flow matched.
MY 2$ greg